反应详情

温度

100 °C

To a suspension of tert-butyl 4-aminobenzoate (6.36 g, 32.9 mmol) and 2,6-dichlorobenzothiazole (5 g, 24.5 mmol) in isopropanol (150 mL) was added 4 N HCl in 1,4-dioxane (4 mL, 16 mmol). The mixture was refluxed at 100° C. for 7 h, and then allowed to cool to room temperature. White precipitates formed during cooling were isolated by filtration to yield the first crop of the title compound as a white solid (3.13 g). The filtrate was concentrated in vacuo and then stirred in a mixed solvent of TEA (20 mL) and CH2Cl2 (20 mL) overnight. The solvent was removed in vacuo, and the residue was triturated with isopropanol/ethyl acetate. The isolated white solid was stirred in a mixed solvent of isopropanol (12 mL) and ethyl acetate (8 mL) for 0.5 h and collected by filtration to yield the second crop of the title compound (3.5 g) (total 6.63 g, 85% yield). HPLC/MS (Method C): retention time=2.51 min, [M+H]+=305.3. 1H NMR (500 MHz, DMSO-d6) δ 11.08 (bs, 1H), 7.98 (d, J=2.20 Hz, 1H), 7.94 (m, 2H), 7.88 (m, 2H), 7.64 (d, J=8.25 Hz, 1H), 7.36 (dd, J=8.80, 2.20 Hz, 1H).

1. temperatureto cool to room temperature
2. customWhite precipitates
3. customformed
4. temperatureduring cooling
5. customwere isolated by filtration